It is known to provide a gaming system which comprises a game controller arranged to randomly display several symbols from a predetermined set of symbols and to determine a game outcome such as a game win based on the displayed symbols. Such gaming systems may commonly be implemented as a stepper machine provided with reels with each reel carrying several symbols of the set, or a video machine wherein selected symbols are displayed on virtual reels on a graphical display device.
While such gaming systems are popular with game players, the ability to modify characteristics of a game and thereby enhance player amusement is limited because the set of symbols is fixed. Indeed, in some jurisdictions in order to comply with gaming regulations it is necessary to keep the reel strip lengths and symbols constant.